Passivhaus EnerPHit certification for existing buildings: What is it and how to achieve it?

As the demand for energy-efficient buildings continues to grow, the retrofit of existing buildings to meet modern efficiency standards has become increasingly important.

Passivhaus EnerPHit certification provides a rigorous and effective framework for deep energy retrofits, ensuring optimal energy performance and comfort. This article outlines the pathways to achieving EnerPHit certification, its advantages, and considerations for partial renovations.

Pathways for achieving EnerPHit certification

There are two primary pathways to achieving EnerPHit certification: performance-based and prescriptive, together with common requirements that apply to both. Let’s take a look at each one.

1. EnerPHit Energy Demand Method

This performance-based approach is similar to Passivhaus certification for new builds but with slightly relaxed heating and cooling demand requirements, adjusted for the seven global climate zones defined by the Passivhaus Institute, shown in Figure 2.

2. EnerPHit Building Component Method

This prescriptive approach sets maximum thermal transmittance values (“U-values”) for each building element, requires control of solar gains, and establishes minimum performance requirements for mechanical ventilation with heat or moisture recovery, depending on the climate zone (Figure 4). The aim is to ensure that the retrofit is highly energy-efficient and safe with respect to moisture-related pathologies.

Common requirements (for both pathways)

For both pathways, there are common requirements. Regarding the level of air infiltration, the maximum allowed value in the airtightness (Blower Door) test is n50 = 1.0 air changes per hour (instead of n50 = 0.6 ach required by Passivhaus for new builds). Additionally, the total renewable primary energy consumption of the building is limited, depending on whether it is certified as EnerPHit Classic, Plus, or Premium (Plus and Premium include renewable energy generation), as shown in Figure 6. Each certification class has its respective seal, shown in Figure 7.

Figure 7: EnerPHit Classic, Plus y Premium seals

Advantages of EnerPHit certification

Pursuing EnerPHit certification provides numerous benefits:

• Holistic deep energy retrofit: Ensures comprehensive upgrades that prevent moisture damage associated with partial retrofits.
• Up to 90% energy savings: Significant reductions in space heating and cooling costs.
• Enhanced indoor air quality: Mechanical ventilation with heat recovery (MVHR) ensures a controlled, fresh, and comfortable air supply.
• Superior thermal comfort: High-performance insulation and airtightness eliminate cold spots and drafts.
• Efficient HVAC systems: Optimized heating, cooling, and hot water systems reduce energy consumption.
• Lower life-cycle carbon emissions: Avoids “lock-in” effects where partial renovations leave high CO2 emissions unaddressed for years.

Step-by-step retrofits and partial renovations

For phased retrofits, buildings can receive pre-certification for all steps up to the final complete retrofit, under an EnerPHit Retrofit Plan (ERP). This ensures that when all phases are complete, the building meets EnerPHit standard. Pre-certification offers reassurance to owners and planners that performance targets will be achieved and helps spread the investment over a longer period.

EnerPHit Unit certification is also available for individual apartments within multi-residential buildings. This requires:

• Airtightness verification: Either a pressure test (qe 50 ≤ 1.0 m³/(hm²)) or detailed documentation and photographic evidence of airtight construction.
• Connection to adjacent spaces: Measures to ensure the retrofit works don’t generate moisture damage in neighbouring units.

Conclusions

EnerPHit offers several pathways to achieve Passivhaus certification. When carrying out an energy retrofit, it’s especially important to implement improvements in a way that avoids moisture damage. EnerPHit certification provides reliable and safe methodologies to avoid this, ensuring that existing buildings meet modern standards of efficiency and comfort, while significantly reducing their environmental impact.